1. Field of the Invention
The present invention relates to an automatic seat belt apparatus in which the height at which a webbing is applied can be adjusted.
2. Description of the Related Art
In conventional, well-known automatic seat belt apparatus of this type, a slider engaged with one end of a webbing is connected to a motor via a continuous elongated member, e.g., a flexible tape or a wire, and can be driven to move along a guide rail. At a portion of the guide rail towards the rear of the vehicle, the slider engages a slider maintaining member, which is connected to a strengthening member of a side wall of the vehicle body, or engages a shoulder anchor, such that the slider can be maintained to the vehicle body. Further, the position at which the slider is maintained to the behicle body can be changed by the position at which the shoulder anchor is connected to the strengthening member being changed along the guide rail.
Accordingly, when a vehicle occupant sits in the vehicle seat and closes the door, the slider moves along the guide rail toward the rear of the vehicle by the driving force of the motor. The slider abuts the shoulder anchor and is maintained thereat, so that the webbing is applied to the vehicle occupant. Thereafter, the maintaining position of the slider, i.e., the height at which the webbing is applied, can be adjusted by the vehicle occupant manually changing the connected position of the shoulder anchor. It is thereby possible for the webbing to be securely applied to vehicle occupants with different builds.
In this conventional automatic seat belt apparatus in which the height at which the webbing is applied is adjustable, the slider, which is maintained to the vehicle body via the shoulder anchor as described above, is connected to the motor via a continuous elongated body. Therefore, when the occupant moves the shoulder anchor together with the slider along the guide rail in order to adjust the height at which the webbing is applied, the motor is also driven via the elongated body. As a result, a large operational force is necessary to adjust the height at which the webbing is applied. There is also a drawback in that the workability is poor. Especially in cases in which a gear, which is attached to the motor and is used for deceleration, is a gear which cannot rotate reversely, the shoulder anchor cannot be moved. It is thereby difficult to adjust the height at which the webbing is applied.
In a prior application (Japanese Utility Model Laid-Open No. 3-55354), the applicant of the present invention proposed an automatic seat belt apparatus in which the elongated member is structured by a first elongated member and a second elongated member. The first elongated member is connected to a motor, and the second elongated member is connected to a slider. The first and second elongated members are connected to each other such that they can be separated from each other. When the slider is engaged with a slider maintaining member, the first and second elongated members are separated. The maintaining position of the slider to the vehicle body can be changed when the first and second elongated members are in this separated state. Therefore, the motor is not driven when the height at which the webbing is applied is adjusted.
In the proposed automatic seat belt apparatus described above, means explained hereinafter are used to connect the first and second elongated members so that they can be separated from each other. First, a lever is disposed between the first and second elongated members. A base end portion of the lever engages an opening formed in the second elongated member. An end claw portion of the lever engages an opening formed in the first elongated member. A spring is used to maintain these engaged states. The lever is urged to rotate towards the opening corresponding to the end claw portion of the lever, with the base end portion of the lever as the center of rotation. A stopper, which is engageable with the lever, is provided on a slider maintaining member. When the webbing is applied, the slider engages the slider maintaining member, and the lever and the stopper are moved closer relatively along the longitudinal direction of the elongated members. The lever and the stopper thereby engage and rotate against the urging force of the spring. Accordingly, the engagement of the end claw portion of the lever and the opening corresponding thereto is cancelled. The first and second elongated members thereby separate. Further, when application of the webbing is released, the lever and the stopper are separated relatively along with the separation of the slider and the slider maintaining member. The lever thereby returns to the angle at which it was originally positioned. The first and second elongated members may thereby be connected again.
When the lever rotates from a connected position, at which the first and second elongated members are connected, to a separated position, at which the first and second elongated members are separated, due to the urging force of the spring, an excessive load is applied to the opening with which the end claw portion of the lever is engaged. In particular, because the end claw portion of the lever moves horizontally with respect to the direction of movement of the first elongated member, the first elongated member can be easily deformed at the opening position. Further, an excessive amount of labor is necessary to manage the precision of strength of the elongated members and the precision of the apparatus.
There are limits to the manufacturing precision of each structural part. Therefore, a case may arise in which, for example, rattling occurs between the stopper and the lever. In this case, it is possible that the engaged state of the lever and the stopper may change. After the first and second elongated members separate, the lever would move from its predetermined angular position. The end claw portion of the lever would then be placed in the path of the first elongated member. In this situation, when the first elongated member moves along the path in order to connect with the second elongated member, the end claw portion of the lever collides with the end portion of the first elongated member. Accordingly, in this case also, the first elongated member can be easily deformed. Further, an excessive amount of labor is necessary to manage the strength of the elongated members and the precision of the apparatus.